Tuberculin Reactivity in Neonates Vaccinated with BCG at Primary Care Clinics: With Two Types of BCG Vaccine and Two Strengths of PPD

Kim, Wan Ju; Lee, Sun Ho; Ahn, Sang Yoon; Yang, Seung Jae; Oh, Sung Hee

Abstract

PURPOSE
The number of newborns vaccinated with BCG of Tokyo 172 strain, which has been claimed to cause lesser degree of local adverse events including scar, has recently been increasing. However, tuberculin response to this vaccine has inadequately been studied, especially with newborns cared at primary care clinics. We, therefore, performed a study in newborns vaccinated with BCG at private pediatric offices and evaluated the response to PPD 2TU or PPD 5TU following vaccination with percutaneous or intradermal BCG.
METHODS
Two hundred infants who had been cared at three private pediatric offices were retrospectively enrolled in the study. One hundred fifty one infants had received percutaneous BCG(Tokyo strain); 129 infants had had tuberuclin test with PPD 2TU and the rest of 22 infants with PPD 5TU. Forty nine infants had received intradermal BCG(28 infants Copenhagen strain, I infant French strain, 20 infants unknown); 35 infants had had tuberculin test with PPD 2TU, 14 infants(11%) with PPD 5TU.
RESULTS
In infants vaccinated with percutaneous BCG, the mean induration diameter in tuberculin test was significantly greater with PPD 5TU(12.4±3.5mm) compared to PPD 2TU (9.2±4.4mm). In infants vaccinated with intradermal BCG, the mean induration diameters in tuberculin test were 5.7±5.1mm to PPD 2TU and 6.6±4.8mm to PPD 5TU, which were not significantly different. The tuberculin response to PPD 2TU was significantly greater in infants vaccinated with percutaneous BCG compared to those with intradermal BCG. The tuberculin response to PPD 5TU was also significantly greater in infants vaccinated with percutaneous BCG compared to those with intradermal BCG.
CONCLUSION
Percutaneous BCG(Tokyo strain) seems to cause greater response to tuberculin compared to intradermal BCG and PPD 2TU induces weaker response compared to PPD 5TU. Acknowledging some discrepancies from the previously reported data, which might have been due to the different source of the study subjects, more studies are needed to establish the range of tuberculin response following BCG vaccination in order to differentiate from tuberculosis.